LaTeX model is different: it doesn't specify the four margins, but rather many more dimensions and deduces the bottom and right (outer) margins from them. With the layout package suggested by Gonzalo Medina you'll see those dimensions. The unit is "printer points": 72.27pt = 1in = 2.54cm
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egregMar 31 '12 at 21:34

1

The answer depends importantly on the text font size (10pt (default), 11pt, and 12pt) and on whether the output is set in single-column or two-column format. To find LaTeX's default values of the margins for each combination of these main options, either use the layout package (as is explained in @GonzaloMedina's answer) or open the files bk10.clo, bk11.clo, and bk12.clo files (.clo is short for "class option") manually and search for the relevant parameters. I recommend using the layout package...
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MicoMar 31 '12 at 21:45

Using the \pagevalues command you will obtain a table of the values
of the current document’s page layout parameters; this, together with the showframe option for the geometry package, can be useful when designing a new page layout. A little example with some "extreme" values just for illustration:

But If I'm not satisfied of margins of my document how can I set them to myself using cm as unit of measure?
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MazzyMar 31 '12 at 21:57

@Mazzy: if you are talking about changing the predefined layout, then use the geometry package. For example, \usepackage[margin=3cm]{geometry} will give you 3cm margins.
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Gonzalo MedinaMar 31 '12 at 21:59

Suppose I would change the margin in this way: odd pages=margin top,bottom,left=3cm and right=3.5cm.even pages=margin top,right,bottom=3cm and left=3.5cm.
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MazzyMar 31 '12 at 22:01

@Mazzy Then you could use something like \usepackage[vmargin=3cm,rmargin=3.5cm,lmargin=3cm]{geometry} and probably you'll need some other options depending on whether the header/footer are to be included or not in the margins. Read the package documentation to learn all the options it offers.
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Gonzalo MedinaMar 31 '12 at 22:10

4

@Mazzy I think you are leaving that 3.5cm margin for binding. If so use \usepackage[bindingoffset=0.5cm,margin=3cm]{geometry}
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Harish KumarMar 31 '12 at 23:15